It’s only infinite in the sense that it’s beyond our measurement. And whether or not it is infinite doesn’t even matter to us because of the speed of light and the expansion of space itself. There is a sphere around us that is all we will ever know or experience or be able to affect. Outside that sphere other things can and do exist, but we are fundamentally separated from them forever. There are entire galaxies we will never see because the light will never reach us. That is wild to me.